I wouldn't say that's the problem I've observed. around 2015 or so I remember consistent useful Quora answers from Quora. it was Yahoo answers but better because people could justify with qualifications. I actually had an account briefly

then I'm not exactly sure when, but definitely by 2018, every answer I ever see on Google is either incorrect, answering the wrong question, or in broken English. commonly all three at once

I don't recall ever seeing a product placement, although admittedly I stopped clicking a long time ago

my educated guess is that due to some likely seo-related concern they deleted/archived/unlisted their old good quality answers in favour of newer more seo-friendly answers

it may not even be their fault, it's possible that Google's algorithm just doesn't drag up older answers from their website, but given my experience with the decision-making in the brief time I was a user there (e.g. removing the ability to add a description to questions) I suspect not